no THE FOREST TENT CATERPILLAR 



of very serious damage ; those with a dot inside, less serious 

 damage, and the simple circles, places where the insects were 

 numerous enough to be noticed by our correspondents, but 

 were not very destructive. It is likely that many of these 

 latter places will have the insects in greater numbers this 

 season. 



An interesting fact brought out by the preparation of this 

 map is that the insects seem to follow rivers closely in their 

 spread from one locality to another. The injury has been most 

 severe along the Connecticut river, where the insects first 

 appeared in destructive numbers about four years ago. 



THE LIFE HISTORY OF THE INSECT 



These Forest Tent Caterpillars pass the winter within the 

 eggshell, the eggs being attached to the twigs in cylindrical 

 rings, more or less covered with a grayish varnish. In spring, 

 when the leaves of the trees begin to unfold, the young cater- 

 pillars gnaw through the eggshells and come forth. They are 



then tiny creatures, 

 scarcely one tenth of 

 an inch long, show- 

 ing under a lens that 

 the blackish body is 

 thickly covered with 

 rather long brown- 

 ish, or grayish, hairs. 

 The tiny caterpillars 

 feed upon the ten- 

 der leaves of the 

 ■ twig near where the 

 egg-mass was placed. 

 In' about two weeks 

 each increases in 

 size to such extent 

 that the skin in 

 which it came from 

 the egg is too small 

 Fig. 39.— Cast skins of Forest Tent Caterpillars. ^°^ '^^- This skin 



